JP2023109330A - Liquid crystal polyester resin, method for producing the same, liquid crystal polyester resin composition, and molded article composed of the same - Google Patents

Abstract

An object of the present invention is to obtain a liquid crystalline polyester resin which is excellent in high cycle moldability while suppressing burrs. The structural unit (I) derived from 6-hydroxy-2-naphthoic acid, the structural unit (II) derived from 4,4'-dihydroxybiphenyl, the structural unit (IV) derived from hydroquinone, ), a liquid crystalline polyester resin containing a structural unit (V) derived from terephthalic acid and satisfying the following formulas (A) to (E). 36≦[I]≦49.8 (A), 5.5<[II]≦15 (B), 1≦[III]≦9 (C), 14≦[IV ] ≤ 25 ... (D), 18 ≤ [V] ≤ 29 ... (E) ([I] to [V] are each structural unit (I ) to (V) content (mol%).) [Selection] None

Description

The present invention relates to a liquid crystalline polyester resin, a liquid crystalline polyester resin composition, and a molded article made thereof. More specifically, it relates to a liquid crystal polyester resin, a liquid crystal polyester resin composition, and a molded article obtained using the same.

Liquid crystalline polyester resins are excellent in heat resistance, fluidity and dimensional stability, and are therefore used in electrical and electronic parts that require these properties. In recent years, due to the miniaturization of smartphones and the like, there has been an increasing demand for high integration, thinning, and low profile of parts. '-Dihydroxybiphenyl, hydroquinone and liquid crystalline polyester resins containing structural units derived from terephthalic acid to achieve both high strength and blister resistance while having excellent fluidity (e.g., Patent Documents 1 to 6 ) has been proposed.

Japanese Patent Application Laid-Open No. 2021-24985 JP 2017-137438 A WO2018/101214 JP 2012-126842 A JP 2015-183159 JP 2015-227404 A

However, when molding a thin molded product, it is necessary to mold at a high injection pressure, and the methods described in Patent Documents 1 to 6 have the problem of damaging the molding machine and the mold, and the injection pressure varies. There was a problem that it was easy to fill and could not be completely filled, and a problem that the shape could not be maintained after heat treatment.

An object of the present invention is to provide a liquid crystalline polyester resin, a liquid crystalline polyester resin composition, and a molded product comprising the same, which can be stably molded at a low injection pressure and has excellent shape stability after heat treatment. .

The present inventors have made intensive studies to solve the above problems, and as a result, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone and terephthalic acid The present inventors have found that a liquid crystalline polyester resin containing a certain amount of structural units can be stably molded at a low injection pressure and has excellent shape stability after heat treatment, and have arrived at the present invention.

Accordingly, the present invention is as follows:
(1) A liquid crystalline polyester resin containing the following structural units (I) to (V) and satisfying the following formulas (A) to (E).
36≦[I]≦49.8 (A)
5.5<[II]≦15 (B)
1≦[III]≦9 (C)
14≦[IV]≦25 (D)
18≦[V]≦29 (E)
([I] to [V] indicate the content (mol%) of each structural unit (I) to (V) with respect to 100 mol% of the total structural units of the liquid crystal polyester resin.)

(2) The liquid crystalline polyester resin according to (1), which further satisfies the following formula (F).
4≦[I]/[II]<7 (F)
(3) The liquid crystalline polyester resin according to (1) or (2), which further satisfies the following formula (G).
46≦[I]≦49.8 (G)
(4) A method for producing the liquid crystalline polyester resin according to any one of (1) to (3) by copolymerizing monomers that give structural units (I) to (V).
(5) A liquid crystalline polyester resin composition containing 10 to 200 parts by weight of a filler per 100 parts by weight of the liquid crystalline polyester resin according to any one of (1) to (3).
(6) A molded article made of the liquid crystalline polyester resin according to any one of (1) to (3) or the liquid crystalline polyester resin composition according to (5).
(7) The molded article according to (6), which is selected from the group consisting of connectors, relays, switches, coil bobbins, and camera module actuator parts.

INDUSTRIAL APPLICABILITY The liquid crystalline polyester resin of the present invention can be stably molded at a low injection pressure, and a molded article having excellent shape stability after heat treatment can be obtained. In particular, it is suitable for molding small electrical and electronic parts.

FIG. 2 is a conceptual diagram showing a perspective view of a molded connector product produced in Examples and a portion where the amount of warpage is measured.

The present invention will be described in detail below.

<Liquid crystal polyester resin>
Liquid crystalline polyester resins are polyesters that form an anisotropic melt phase. Examples of such polyester resins include polyesters composed of structural units selected from oxycarbonyl units, dioxy units, dicarbonyl units, etc. described later so as to form an anisotropic melt phase.

Next, structural units constituting the liquid crystal polyester resin will be described.
The liquid crystalline polyester resin of the present invention contains 36 mol % or more of the following structural unit (I) as an oxycarbonyl unit with respect to 100 mol % of all structural units of the liquid crystalline polyester resin. Structural unit (I) is a structural unit derived from p-hydroxybenzoic acid. If the structural unit (I) is less than 36 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after the heat treatment. Structural unit (I) is more preferably 40 mol% or more, still more preferably 43 mol% or more, even more preferably 46 mol% or more, from the viewpoint of stable molding at a low injection pressure and excellent shape stability after heat treatment. is particularly preferred.

On the other hand, the liquid crystalline polyester resin of the present invention contains 49.8 mol % or less of the structural unit (I) with respect to 100 mol % of the total structural units of the liquid crystalline polyester resin. If the structural unit (I) is more than 49.8 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after heat treatment. The structural unit (I) is preferably 49.4 mol % or less, more preferably 49 mol % or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

The liquid crystalline polyester resin of the present invention contains more than 5.5 mol % of the following structural unit (II) as an oxycarbonyl unit with respect to 100 mol % of all structural units of the liquid crystalline polyester resin. Structural unit (II) is a structural unit derived from 6-hydroxy-2-naphthoic acid. If the structural unit (II) is 5.5 mol % or less, the injection pressure will be significantly increased and will not be stable, and the shape will change significantly after the heat treatment. The structural unit (II) is preferably 6 mol % or more, more preferably 7 mol % or more, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

On the other hand, the liquid crystalline polyester resin of the present invention contains 15 mol % or less of the structural unit (II) with respect to 100 mol % of the total structural units of the liquid crystalline polyester resin. If the structural unit (II) is more than 15 mol %, the injection pressure will not be stable, and the shape will change significantly after heat treatment. The structural unit (II) is preferably 13 mol % or less, more preferably 11 mol % or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

The liquid crystalline polyester resin of the present invention can be stably molded at a low injection pressure and has excellent shape stability after heat treatment, so the molar ratio of the content of structural units (I) and (II) ([I ]/[II]) is preferably 4 or more, more preferably 4.5 or more, and even more preferably 5 or more. On the other hand, [I]/[II] is preferably less than 7, more preferably 6.5 or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

In addition, as the oxycarbonyl unit, a structural unit derived from m-hydroxybenzoic acid or the like can be used as long as the effects of the present invention are not impaired.

The liquid crystalline polyester resin of the present invention contains 1 mol % or more of the following structural unit (III) as a dioxy unit with respect to 100 mol % of all structural units of the liquid crystalline polyester resin. Structural unit (III) is a structural unit derived from 4,4'-dihydroxybiphenyl. If the structural unit (III) is less than 1 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after the heat treatment. The structural unit (III) is preferably 2 mol % or more, more preferably 3 mol % or more, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

On the other hand, the liquid crystalline polyester resin of the present invention contains 9 mol % or less of the following structural unit (III) with respect to 100 mol % of all structural units of the liquid crystalline polyester resin. If the structural unit (III) is more than 9 mol %, the injection pressure will not be stable, and the shape will change significantly after heat treatment. The structural unit (III) is preferably 8 mol % or less, more preferably 7 mol % or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

The liquid crystalline polyester resin of the present invention contains 14 mol % or more of the following structural unit (IV) as a dioxy unit with respect to 100 mol % of the total structural units of the liquid crystalline polyester resin. Structural unit (IV) is a structural unit derived from hydroquinone. If the structural unit (IV) is less than 14 mol %, the injection pressure will not be stable, and the shape will change significantly after the heat treatment. The structural unit (III) is preferably 15 mol % or more, more preferably 16 mol % or more, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

On the other hand, the liquid crystalline polyester resin of the present invention contains 25 mol % or less of the structural unit (IV) with respect to 100 mol % of the total structural units of the liquid crystalline polyester resin. If the structural unit (IV) is more than 25 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after heat treatment. The structural unit (IV) is preferably 24 mol % or less, more preferably 23 mol % or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

The liquid crystalline polyester resin of the present invention can be stably molded at a low injection pressure and has excellent shape stability after heat treatment, so the molar ratio of the structural units (III) and (IV) ([III ]/[IV]) is preferably 0.1 or more, more preferably 0.15 or more, and even more preferably 0.2 or more. On the other hand, from the viewpoint of stable molding at a low injection pressure and excellent shape stability after heat treatment, [III]/[IV] is preferably 0.6 or less, more preferably 0.55 or less, and 0 0.5 or less is more preferable.

Other dioxy units include resorcinol, t-butylhydroquinone, phenylhydroquinone, chlorohydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4′-dihydroxybiphenyl, 2,2-bis(4- hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, and other aromatic diol-derived structural units; ethylene; Structural units derived from aliphatic diols such as glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; Structural units derived from cyclic diols can be used as long as the effects of the present invention are not impaired.

The liquid crystalline polyester resin of the present invention contains 18 mol % or more of the following structural unit (V) as a dicarbonyl unit with respect to 100 mol % of all structural units of the liquid crystalline polyester resin. Structural unit (V) is a structural unit derived from terephthalic acid. If the structural unit (V) is less than 18 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after the heat treatment. The structural unit (V) is preferably 19 mol % or more, more preferably 20 mol % or more, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

On the other hand, the liquid crystalline polyester resin of the present invention contains 29 mol % or less of the structural unit (V) with respect to 100 mol % of the total structural units of the liquid crystalline polyester resin. If the structural unit (V) is more than 29 mol %, the injection pressure will be greatly increased and will not be stable, and the shape will change significantly after heat treatment. The structural unit (V) is preferably 28 mol % or less, more preferably 27 mol % or less, from the viewpoints of stable molding at a low injection pressure and excellent shape stability after heat treatment.

Other dicarbonyl units include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 1,2- Aromatic dicarboxylic acids such as bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid and 4,4'-diphenyletherdicarboxylic acid Structural units derived from; structural units derived from aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydroterephthalic acid; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, etc. can be used as long as the effects of the present invention are not impaired.

In addition to the structural units (I) to (V), structural units generated from p-aminobenzoic acid, p-aminophenol, etc. are used in the liquid crystal polyester resin within a range that does not impair the effects of the present invention. can do.

The liquid crystalline polyester resin of the present invention can be stably molded at a low injection pressure and has excellent shape stability after heat treatment. Therefore, the total amount of the structural units (I) to (V) is 98 mol% or more. is preferably 99 mol % or more, more preferably 100 mol %.

Further, the ratio of the total amount of the structural units (III) and (IV) to the content of the structural unit (V) (([III]+[IV])/[V]) is from the viewpoint of polymerizability control. , preferably 0.9 or more and 1.1 or less, more preferably 1.0.

The raw material monomers constituting each structural unit are not particularly limited as long as they have a structure capable of forming each structural unit. In addition, acylated products of hydroxyl groups of such monomers, esterified products of carboxyl groups, acid halides, carboxylic acid derivatives such as acid anhydrides, and the like may also be used.

The method for calculating the content of each structural unit in the liquid crystal polyester resin is shown below. First, after pulverizing the liquid crystal polyester resin, tetramethylammonium hydroxide is added, and the thermal decomposition GC/MS measurement is performed using Shimadzu GCMS-QP5050A. The content of structural units not detected or below the detection limit is calculated as 0 mol %.

From the viewpoint of heat resistance, the melting point (Tm) of the liquid crystal polyester resin is preferably 280° C. or higher, more preferably 300° C. or higher, and even more preferably 320° C. or higher. On the other hand, from the viewpoint of workability, the melting point (Tm) of the liquid crystal polyester resin is preferably 370° C. or lower, more preferably 360° C. or lower, and even more preferably 350° C. or lower.

The melt viscosity of the liquid crystalline polyester resin is preferably 3 Pa s or more, more preferably 5 Pa s or more, more preferably 7 Pa s or more, because it can be molded at a stable injection pressure and has excellent shape stability after heat treatment. More preferred. On the other hand, from the viewpoint of low injection pressure, the melt viscosity of the liquid crystalline polyester resin is preferably 50 Pa·s or less, preferably 30 Pa·s or less, and more preferably 20 Pa·s or less.

This melt viscosity is a value measured with a Koka flow tester at a temperature of the melting point (Tm) of the liquid crystalline polyester resin +20°C and a shear rate of 1000/sec.

<Method for producing liquid crystal polyester resin>
The method for producing the liquid crystalline polyester resin of the present invention includes a method of copolymerizing the monomers giving the structural units (I) to (V) in a content within the above range, and a method of obtaining the structural units (I) to (V). There is a method in which two or more types of liquid crystalline polyester resins obtained by copolymerizing with a content outside the above range are blended to make the structural units (I) to (V) within the above range. Since it is possible to stably mold at a low injection pressure without inheriting the properties of the previous liquid crystalline polyester resin, and it is excellent in shape stability after heat treatment, monomers that give structural units (I) to (V) are A method of obtaining by copolymerizing the content in the above range is preferred.

The method for producing the liquid crystalline polyester resin of the present invention can be produced according to a known polyester polycondensation method. Specifically, structural units derived from p-hydroxybenzoic acid, structural units derived from 6-hydroxy-2-naphthoic acid, structural units derived from 4,4′-dihydroxybiphenyl, structural units derived from hydroquinone, and a liquid crystal polyester resin composed of structural units derived from terephthalic acid.

(1) Producing a liquid crystalline polyester resin from p-acetoxybenzoic acid, 6-acetoxy-2-naphthoic acid, 4,4′-diacetoxybiphenyl, 1,4-diacetoxybenzene and terephthalic acid by deacetic acid condensation polymerization reaction Method.

(2) p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, 1,4-diacetoxybenzene and terephthalic acid are reacted with acetic anhydride to acetylate phenolic hydroxyl groups After that, a method for producing a liquid crystalline polyester resin by deacetic acid polymerization.

(3) A method of producing a liquid crystalline polyester resin from phenyl p-hydroxybenzoate, phenyl 6-hydroxy-2-naphthoate, 4,4'-dihydroxybiphenyl, hydroquinone and diphenyl terephthalate by dephenol polycondensation reaction.

(4) p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid and terephthalic acid are reacted with a predetermined amount of diphenyl carbonate to obtain phenyl esters, respectively, and then 4,4′-dihydroxybiphenyl and hydroquinone are added; A method for producing a liquid crystalline polyester resin by a dephenol polycondensation reaction.

Among them, (2) p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4′-dihydroxybiphenyl, 1,4-diacetoxybenzene and terephthalic acid are reacted with acetic anhydride to convert phenolic hydroxyl groups. A method of producing a liquid crystalline polyester resin by deacetic acid polymerization after acetylation is preferably used from the viewpoint of being industrially excellent in controlling the degree of polymerization of the liquid crystalline polyester resin.

As a method for producing the liquid crystalline polyester resin used in the present invention, it is also possible to complete the polycondensation reaction by a solid phase polymerization method. Examples of the treatment by solid phase polymerization include the following methods. First, a liquid crystalline polyester resin polymer or oligomer is pulverized by a pulverizer. The pulverized polymer or oligomer is heated under a stream of nitrogen or under reduced pressure to polycondense to the desired degree of polymerization to complete the reaction. The heating is preferably carried out at a melting point of -50°C to -5°C (for example, 200 to 300°C) for 1 to 50 hours.

The polycondensation reaction of the liquid crystalline polyester resin proceeds without a catalyst, but stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, metal magnesium, etc. can also be used as catalysts.

<Filling material>
The liquid crystalline polyester resin of the present invention may contain a filler in order to impart mechanical strength and other properties to the liquid crystalline polyester resin. The filler used in the present invention is not particularly limited, but examples thereof include fibrous, whisker-shaped, plate-shaped, powdery, granular fillers, and the like. Specifically, fibrous and whisker-like fillers include glass fibers, PAN-based and pitch-based carbon fibers, stainless steel fibers, metal fibers such as aluminum fibers and brass fibers, aromatic polyamide fibers and liquid crystal polyester fibers. Organic fiber, gypsum fiber, ceramic fiber, asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker , and acicular titanium oxide. Plate-like fillers include mica, talc, kaolin, glass flakes, clay, molybdenum disulfide, and wollastonite. Examples of powdery and granular fillers include silica, glass beads, titanium oxide, zinc oxide, calcium polyphosphate and graphite. The surface of the filler used in the present invention may be treated with a known coupling agent (eg, silane coupling agent, titanate coupling agent, etc.) or other surface treatment agent. Two or more of the above fillers used in the present invention may be used in combination.

Among the above fillers, it is preferable to use glass fiber from the viewpoint of excellent mechanical strength such as tensile strength and bending strength, heat resistance, and dimensional stability. The type of glass fiber is not particularly limited as long as it is generally used for reinforcing resins, and examples thereof include long fiber type, short fiber type chopped strands and milled fibers. Moreover, it is preferable to use a plate-like filler from the viewpoint of excellent thin wall fluidity.

The surface of the filler may be treated with a known coupling agent (eg, silane coupling agent, titanate coupling agent, etc.) or other surface treatment agent. Further, the glass fibers may be coated or bundled with a thermoplastic resin such as ethylene/vinyl acetate copolymer or a thermosetting resin such as epoxy resin.

The liquid crystalline polyester resin composition of the present invention further contains antioxidants, heat stabilizers (for example, hindered phenols, hydroquinones, phosphites, thioethers and substituted products thereof), as long as the effects of the present invention are not impaired. UV absorbers (e.g., resorcinol, salicylates), anti-coloring agents such as phosphites and hypophosphites, lubricants and release agents (montanic acid and its metal salts, its esters, its half esters, stearyl alcohol, stearamide and polyethylene wax), coloring agents containing dyes or pigments, carbon black as a conductive agent or coloring agent, crystal nucleating agents, plasticizers, flame retardants (bromine flame retardants, phosphorus flame retardants, red phosphorus, silicone flame retardants) retardants, etc.), flame retardant aids, and antistatic agents.

In the liquid crystal polyester resin composition of the present invention, the content of the filler is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the liquid crystal polyester resin. If the filler content is 10 parts by weight or more, the mechanical strength of the molded product can be improved. 15 parts by weight or more is more preferable, and 20 parts by weight or more is even more preferable. On the other hand, if the filler content is 200 parts by weight or less, it is preferable because a liquid crystalline polyester resin composition which is excellent in moldability and thin-wall fluidity and can be easily injection-molded into small-sized thin-wall molded articles can be obtained. 150 parts by weight or less is more preferable, and 100 parts by weight or less is even more preferable.

Examples of the method of blending the above fillers and additives include a dry blending method of blending a filler and other solid additives into a liquid crystal polyester resin, and a method of blending a filler and other liquid additives into a liquid crystal polyester resin. A method of adding fillers and other additives during polymerization of the liquid crystalline polyester resin, and a method of melt-kneading the fillers and other additives into the liquid crystalline polyester resin can be used. Among them, the method of melt-kneading is preferable.

A known method can be used for the melt-kneading. Examples include Banbury mixers, rubber roll machines, kneaders, single-screw or twin-screw extruders, and the like. Among them, a twin-screw extruder is preferred. The melt-kneading temperature is preferably higher than the melting point of the liquid crystal polyester resin and lower than the melting point +50°C.

As kneading methods, there are 1) a method in which the liquid crystalline polyester resin, fillers and other additives are added all at once from a feeder and kneaded together (batch kneading method), and 2) the liquid crystalline polyester resin and other additives are initially charged. A method in which a filler and other additives are added from a side feeder and kneaded after being fed from a feeder and kneaded (side feed method), 3) A liquid crystalline polyester composition containing a liquid crystalline polyester resin and other additives at a high concentration A method of preparing a product (master pellets) and then kneading the master pellets with a liquid crystal polyester resin and a filler so as to have a specified concentration (master pellet method). Methods for adding fillers and other additives include batch kneading, sequential addition, and addition of a high-concentration composition (master), and any method may be used.

<Molded product>
The liquid crystalline polyester resin and the liquid crystalline polyester resin composition of the present invention can be produced by a molding method such as injection molding, extrusion molding, press molding, solution casting, spinning, or the like, thereby exhibiting excellent surface appearance (color tone), mechanical properties, and heat resistance. It is possible to process it into a molded product having properties. The molded products here include injection molded products, extrusion molded products, press molded products, sheets, pipes, various films such as unstretched films, uniaxially stretched films, biaxially stretched films, unstretched yarns, super stretched yarns, etc. Examples include various fibers. Injection molding is particularly preferred from the viewpoint of workability. In the case of melt molding, from the viewpoint of suppressing deterioration of the liquid crystal polyester resin composition and improving mechanical strength, the melt molding is preferably performed at 370° C. or lower, more preferably 360° C. or lower.

Molded articles obtained by molding the liquid crystalline polyester resin and the liquid crystalline polyester resin composition of the present invention can be preferably used as electric/electronic parts. Examples of electrical and electronic components include PCs, GPS built-in devices, mobile phones, millimeter wave and quasi-millimeter wave radars such as collision avoidance radars, and flexible printed circuit boards used for antennas of mobile communication and electronic devices such as tablets and smartphones. , circuit boards for lamination, printed wiring boards and three-dimensional circuit boards; lamp reflectors and lamp sockets such as LEDs, communication base station small cells and micro cell members for mobile communication terminals, antenna covers, housings, sensors, actuators for camera modules Components, connectors, relay cases and bases, switches, coil bobbins, capacitors, etc. In particular, it is useful for connectors, relays, switches, coil bobbins, camera module actuator parts, etc., because it can be molded stably at a low injection pressure and has excellent shape stability after heat treatment.

EXAMPLES The present invention will be described below using examples, but the present invention is not limited by the examples. In the examples, the composition and property evaluation of the liquid crystalline polyester resin were measured by the following methods.

(1) Composition analysis of liquid crystal polyester resin To 0.1 mg of pulverized liquid crystal polyester resin pellets, 2 μL of tetramethylammonium hydroxide 25% methanol solution is added, and pyrolysis GC / MS measurement is performed using Shimadzu GCMS-QP5050A. , the composition ratio of each component in the liquid crystal polyester resin was determined.

(2) Melting point (Tm) measurement of liquid crystalline polyester By a differential scanning calorimeter DSC-7 (manufactured by PerkinElmer), the endothermic peak temperature observed when the liquid crystalline polyester resin is heated from room temperature at a temperature increase of 20 ° C./min. After the observation of (Tm ₁ ), it was held at a temperature of Tm ₁ +20° C. for 5 minutes, then cooled to room temperature once under a temperature decrease condition of 20° C./min, and then observed when heated again under a temperature increase condition of 20° C./min. The endothermic peak temperature was taken as the melting point (Tm).

(3) Melt viscosity of liquid crystal polyester resin Using a flow tester CFT-500D (orifice 0.5φ × 10 mm) (manufactured by Shimadzu Corporation), at Tm + 20 ° C., under the conditions of a shear rate of 1000 / s. Melt viscosity was measured.

(4) Evaluation of injection pressure and its stability After drying the liquid crystal polyester resin at 150 ° C. for 3 hours using a hot air dryer, it is subjected to a Fanuc α30C injection molding machine (manufactured by Fanuc), and the cylinder temperature is adjusted to that of the liquid crystal polyester resin. Injection molding was performed under conditions of a melting point +20°C, a mold temperature of 90°C, and an injection speed of 400 mm/s. 3 mm) is filled with liquid crystalline polyester resin, the pitch between terminals is 0.4 mm, the minimum thickness of the product (partition 3) is 0.2 mm, and the outer dimensions are 3 mm (width) x 2 mm (height) x 30 mm (length). The peak pressure during molding when the product was obtained was obtained. This was performed for 100 shots, and the average value of the peak pressure was taken as the injection pressure, and the standard deviation of the peak pressure was taken as the stability. FIG. 1a is a perspective view of the connector molding.

(5) Evaluation of shape stability after heat treatment After drying the liquid crystal polyester resin at 150 ° C. for 3 hours using a hot air dryer, it is subjected to a Fanuc α30C injection molding machine (manufactured by Fanuc), and the cylinder temperature is set to the melting point of the liquid crystal polyester resin. The temperature was set to +20° C., the mold temperature was set to 90° C., the injection pressure was set to 100 MPa, and the speed was set to the minimum filling speed to obtain a connector molded product similar to (4). The obtained connector molded product was left in an oven heated to 260° C. for 3 minutes, and the amount of warp after the heat treatment of the connector molded product was measured. The amount of warpage was determined by measuring the dimensional difference from a straight line connecting both ends of the elongated molded product in the longitudinal direction. FIG. 1b is a conceptual diagram showing a portion where the amount of warp is measured in the elongated molded product, and the amount of warp is defined as the difference between the AB plane as a reference plane a and the maximum deformation plane b. The smaller the amount of warpage, the better the shape stability.

[Example 1]
792 parts by weight of p-hydroxybenzoic acid (HBA), 198 parts by weight of 6-hydroxy-2-naphthoic acid (HNA), 4,4′-dihydroxybiphenyl (DHB) were placed in a 5 L reaction vessel equipped with a stirring blade and a distillation tube. ) 109 parts by weight, 206 parts by weight of hydroquinone (HQ), 408 parts by weight of terephthalic acid (TPA) and 1314 parts by weight of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups) were charged, and stirred under a nitrogen gas atmosphere to 145 parts by weight. C. for 120 minutes, and then the temperature was raised from 145.degree. C. to 360.degree. C. over 4 hours. Thereafter, the polymerization temperature was maintained at 360° C., the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, the reaction was continued, and polymerization was completed when a predetermined stirring torque was reached. Next, the polymer was extruded in a strand form through a nozzle having a circular ejection port with a diameter of 6 mm, and pelletized by a cutter to obtain a liquid crystalline polyester resin (A-1).

[Example 2]
A liquid crystalline polyester resin (A-2) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 598 parts by weight of HBA, 330 parts by weight of HNA, 44 parts by weight of DHB, 283 parts by weight of HQ, and 467 parts by weight of TPA.

[Example 3]
A liquid crystalline polyester resin (A-3) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 792 parts by weight of HBA, 132 parts by weight of HNA, 185 parts by weight of DHB, 180 parts by weight of HQ, and 437 parts by weight of TPA.

[Example 4]
A liquid crystalline polyester resin (A-4) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 743 parts by weight of HBA, 176 parts by weight of HNA, 153 parts by weight of DHB, 206 parts by weight of HQ, and 447 parts by weight of TPA.

[Example 5]
Liquid crystalline polyester resin (A-5) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 663 parts by weight of HBA, 154 parts by weight of HNA, 174 parts by weight of DHB, 232 parts by weight of HQ, and 505 parts by weight of TPA.

[Example 6]
A liquid crystalline polyester resin (A-6) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 776 parts by weight of HBA, 264 parts by weight of HNA, 65 parts by weight of DHB, 219 parts by weight of HQ, and 389 parts by weight of TPA.

[Comparative Example 1]
A liquid crystalline polyester resin (A'-7) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 711 parts by weight of HBA, 176 parts by weight of DHB, 240 parts by weight of HQ, 168 parts by weight of TPA, and 467 parts by weight of TPA.

[Comparative Example 2]
Liquid crystalline polyester resin (A'-8) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 711 parts by weight of HBA, 88 parts by weight of HNA, 261 parts by weight of DHB, 180 parts by weight of HQ, and 505 parts by weight of TPA.

[Comparative Example 3]
A liquid crystalline polyester resin (A'-9) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 517 parts by weight of HBA, 220 parts by weight of HNA, 174 parts by weight of DHB, 271 parts by weight of HQ, and 350 parts by weight of TPA.

[Comparative Example 4]
A liquid crystalline polyester resin (A'-10) was obtained in the same manner as in Example 1, except that the monomer charge was changed to 857 parts by weight of HBA, 242 parts by weight of HNA, 65 parts by weight of DHB, 193 parts by weight of HQ, and 350 parts by weight of TPA.

Table 1 shows the evaluation results of the above (1) to (5) for the liquid crystal polyester resins obtained in Examples 1 to 6 and Comparative Examples 1 to 4.

A filler was further added to the liquid crystalline polyester resins obtained in Examples 1 to 6 and Comparative Examples 1 to 4 to prepare liquid crystalline polyester resin compositions. Fillers used in Examples and Comparative Examples are shown below.
Filler (B)
(B-1) Milled fiber manufactured by Nippon Electric Glass (40M-10A)
(B-2) Mica made by Yamaguchi Mica (A-21)

[Example 7, Comparative Example 5]
Using a Toshiba Machine TEM35B twin-screw extruder equipped with a side feeder, the liquid crystalline polyester resins (A-1, A'-7) obtained in each production example were charged from the hopper at the compounding amounts shown in Table 2, and filled. Materials (B-1, B-2) were charged from a side feeder in the compounding amounts shown in Table 2, and the cylinder temperature was set to the melting point of the liquid crystalline polyester resin +10° C., and melt-kneaded to obtain pellets. The obtained pellets of the liquid crystal polyester resin composition were dried with hot air and then evaluated in the same manner as in (4) and (5). Table 2 shows the results.

From the results in Tables 1 and 2, by using a liquid crystal polyester resin containing a predetermined amount of structural units (I) to (V) or a liquid crystal polyester resin composition using the resin, molding can be performed stably at a low injection pressure. It is possible to obtain a molded article having excellent shape stability after heat treatment.

INDUSTRIAL APPLICABILITY The liquid crystalline polyester resin and liquid crystalline polyester resin composition of the present invention can be stably molded at a low injection pressure and have excellent shape stability after heat treatment. It is suitable for electrical and electronic parts such as parts and mechanical parts.

1 Long side 2 Short side 3 Length 30 mm
4 height 2mm
5 width 3mm
6 pitch distance 0.4mm
7 Minimum thickness 0.2mm
8 Warp amount G1 Pin gate a Reference surface b Maximum deformation surface

Claims (7)

A liquid crystalline polyester resin containing the following structural units (I) to (V) and satisfying the following formulas (A) to (E).
36≦[I]≦49.8 (A)
5.5<[II]≦15 (B)
1≦[III]≦9 (C)
14≦[IV]≦25 (D)
18≦[V]≦29 (E)
([I] to [V] indicate the content (mol%) of each structural unit (I) to (V) with respect to 100 mol% of the total structural units of the liquid crystal polyester resin.)

2. The liquid crystalline polyester resin according to claim 1, further satisfying the following formula (F).
4≦[I]/[II]<7 (F) 3. The liquid crystalline polyester resin according to claim 1, further satisfying the following formula (G).
46≦[I]≦49.8 (G) A method for producing the liquid crystalline polyester resin according to any one of claims 1 to 3 by copolymerizing monomers that give structural units (I) to (V). A liquid crystal polyester resin composition containing 10 to 200 parts by weight of a filler with respect to 100 parts by weight of the liquid crystal polyester resin according to any one of claims 1 to 3. A molded article comprising the liquid crystalline polyester resin according to any one of claims 1 to 3 or the liquid crystalline polyester resin composition according to claim 5. 7. The molded article according to claim 6, wherein the molded article is any one selected from the group consisting of connectors, relays, switches, coil bobbins, and camera module actuator parts.

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